Impact of seawater carbonate variables on post-larval bivalve calcification

Several studies have demonstrated that shellfish calcification rate has been impacted by ocean acidification. However, the carbonate system variables responsible for regulating calcification rate are controversial. To distinguish the key variables, we manipulated a seawater carbonate system by regulating seawater pH and dissolved inorganic carbon(DIC). Calcification rates of juvenile blue mussel(M ytilus edulis) and Zhikong scallop(C hlamys farreri) were measured in different carbonate systems. Our results demonstrated that neither [HCO ˉ^+ 3 ], DIC, or p H([H ^+ ]) were determining factors for the shellfish calcification rate of blue mussel or Zhikong scallop. However, a significant correlation was detected between calcification rate and DIC/[H ^+ ] and [CO_3^(2ˉ)] in both species.

The potential of ocean acidification on suppressing larval development in the Pacific oyster Crassostrea gigas and blood cockle Area inflata Reeve

We evaluated the effect of pH on larval development in larval Pacific oyster(Crassostrea gigas) and blood cockle(Arca inflata Reeve).The larvae were reared at pH 8.2(control),7.9,7.6,or 7.3beginning 30 min or 24 h post fertilization.Exposure to lower pH during early embryonic development inhibited larval shell formation in both species.Compared with the control,larvae took longer to reach the D-veliger stage when reared under pH 7.6 and 7.3.Exposure to lower pH immediately after fertilization resulted in significantly delayed shell formation in the Pacific oyster larvae at pH 7.3 and blood cockle larvae at pH 7.6 and 7.3.However,when exposure was delayed until 24 h post fertilization,shell formation was only inhibited in blood cockle larvae reared at pH 7.3.Thus,the early embryonic stages were more sensitive to acidified conditions.Our results suggest that ocean acidification will have an adverse effect on embryonic development in bivalves.Although the effects appear subtle,they may accumulate and lead to subsequent issues during later larval development.